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Security Services

Microsoft Internet Explorer Use-after-Free Vulnerability



Internet Explorer is Microsoft's web browser for the Windows platform.


Remote exploitation of a use-after-free vulnerability in Microsoft Corp.'s Internet Explorer could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability is triggered when the center element is dynamically modified via JavaScript code. When this occurs, an HTML object is freed, while a reference to it remains. This reference is later reused, potentially leading to stale data being accessed. The result of this could allow an attacker to execute arbitrary code.


Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user viewing the Web page. To exploit this vulnerability, a targeted user must load a malicious Web page that an attacker created. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites. After a user visits the malicious Web page, no further user interaction is needed.


Internet Explorer versions 6, 7, and 8 are vulnerable.


Since the vulnerability is triggered through JavaScript, disabling ActiveScript code on untrusted sites will prevent the exploitation of this vulnerability.


Microsoft Corp. has released patches which addresses this issue. For more information, consult their advisory at the following URL:


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-1523 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


03/07/2012 Initial Vendor Notification
03/07/2012 Initial Vendor Reply
06/12/2012 Coordinated Public Disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2012 Verisign, Inc.

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